Robot Framework test data is defined in tabular format, using either hypertext markup language (HTML), tab-separated values (TSV), plain text, or reStructuredText (reST) formats. The details of these formats, as well as the main benefits and problems with them, are explained in the subsequent sections. Which format to use depends on the context, but the plain text format is recommended if there are no special needs.
最优一句说的很明白了,如果没有特殊的需求,推荐使用plain text格式来写,也就是txt格式。